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Old 2004-08-16, 09:30   #13
biwema's Avatar
Mar 2004

3·127 Posts

I also downloaded and tested the new version of prp. For me, it is about 3 times faster! (19*2^531k+1; 32k FFT)
Congratulations, George!

Just one thing seems somewhat strange. (k*2^exp+1)
If I use k=19, I can go beyond exp=595000 and it still uses 32k FFT.
If I use K=10000 or so, it switches already below exp=447000 from 32K FFT to 48K FFT. with k=3 exponents upt to 638000 are possible with 32k FFT.

in the k*2^exp-1 we have more FFT lengths:
k=19 has 32kFFT up to 601000;
k=3 up to 645000 and k= 10000 up to 453000.
In the minus mode, more FFT sizes are available (28K and 40K instead of only 24K and 40K besides 32K).

Is that normal, that the threshholds of the fft sizes depend so greatly on the size of the k (mantissa)? If we use k=3 instead of 10000, the the difference is just 13 bits.
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